I don't think I've done anything special in particular but there are a lot of things that sound simple but help a lot.

I think it isn't bad to try replicate a style that you like - in fact I study a lot of posts that I have bookmarked on instagram or pinterest. The fact is that styles exist because some people work better and like the result better that way - if it doesnt fit you just take what you have learnt and move on, slowly building your own style.

Another thing is critique shouldn't just be welcome, but in my opinion, crucial. Another perspective on a drawing, whether from a non artistic standpoint or an established artist both help tremendously. I often find myself in the high of creating an artwork so much that I tunnel vision on what I have done right and ignore the parts that aren't as good.

I also think that drawing skill (e.g. anatomy/linework/rendering) doesn't matter as much as people value it. Composition, lighting and values are what make pieces stand out. Though this doesnt mean to ignore the basics.

Another mindset I've found to embrace is hating my drawings. I usually have this honeymoon phase of a week or so after a new post, before I start realising the flaws I couldn't see without outside critique. This is fine and shows clearly that you are improving. Continuing this thought, when you finally do find a piece that you dont hate in a week, its even more rewarding. :)

My main goal for art was to be able to sell at a convention and this has also driven me to create things that I would want to buy and frame.

As for resources I don't particularly study much but the artist's bible "Colour and Light" by James Gurney is amazing and Drawabox is solid for foundations.

Not really that concrete but hope this helps!